Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative - Open-File Report 2020-1042
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Mineral Resources Program Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative Open-File Report 2020–1042 U.S. Department of the Interior U.S. Geological Survey
Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative By Albert H. Hofstra and Douglas C. Kreiner Mineral Resources Program Open-File Report 2020–1042 U.S. Department of the Interior U.S. Geological Survey
U.S. Department of the Interior DAVID BERNHARDT, Secretary U.S. Geological Survey James F. Reilly II, Director U.S. Geological Survey, Reston, Virginia: 2020 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit https://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov/. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Hofstra, A.H., and Kreiner, D.C., 2020, Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative: U.S. Geological Survey Open-File Report 2020–1042, 24 p., https://doi.org/10.3133/ofr20201042. ISSN 2331-1258 (online)
iii Acknowledgments This report benefited from discussions with numerous Mineral Resources Program personnel. We thank Nora Foley (U.S. Geological Survey [USGS]), William Lassetter (Virginia Geological Survey), and Lukas Zurcher (USGS) for early reviews of the Systems-Deposits-Commodities- Critical Minerals Table, as well as Laurel Woodruff (USGS) and Jamey Jones (USGS) for their constructive reviews of this report.
v
Contents
Acknowledgments����������������������������������������������������������������������������������������������������������������������������������������iii
Abstract�����������������������������������������������������������������������������������������������������������������������������������������������������������1
Background����������������������������������������������������������������������������������������������������������������������������������������������������1
Problem and Solution������������������������������������������������������������������������������������������������������������������������������������1
Mineral Systems��������������������������������������������������������������������������������������������������������������������������������������������2
Table Rationale and Explanation�����������������������������������������������������������������������������������������������������������������2
Table Structure��������������������������������������������������������������������������������������������������������������������������������������6
Table Use������������������������������������������������������������������������������������������������������������������������������������������������6
References Cited�����������������������������������������������������������������������������������������������������������������������������������������17
Figures
1. Diagrams showing mineral system concepts��������������������������������������������������������������������������3
2. Schematic cross sections of a porphyry copper-molybdenum-gold system at
various scales�������������������������������������������������������������������������������������������������������������������������������4
3. Schematic model of a basin brine path system�����������������������������������������������������������������������5
Table
1. Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping
Resources Initiative����������������������������������������������������������������������������������������������������������������������7
Conversion Factors
International System of Units to U.S. customary units
Multiply By To obtain
Length
kilometer (km) 0.6214 mile (mi)
Area
square kilometer (km2) 0.3861 square mile (mi2)
Abbreviations
Earth MRI Earth Mapping Resources Initiative
PGE platinum group elements
REE rare earth elements
USGS U.S. Geological Surveyvi
Chemical Symbols
Ag silver
Al aluminum
Ag silver
Al aluminum
As arsenic
Au gold
BaSO4 barite
Be beryllium
Bi bismuth
C graphite
CaF2 fluorspar
Co cobalt
Cr chromium
Cs cesium
Cu copper
Fe iron
Ga gallium
Ge germanium
He helium
Hf hafnium
In indium
KCl potash
Li lithium
Mg magnesium
Mn manganese
Mo molybdenum
Nb niobium
Ni nickel
P phosphorus
Pb lead
Rb rubidium
Re rhenium
Sb antimony
Sc scandiumvii Sn tin Sr strontium Ta tantalum Te tellurium Ti titanium U uranium V vanadium W tungsten Zn zinc Zr zirconium
Systems-Deposits-Commodities-Critical Minerals Table
for the Earth Mapping Resources Initiative
By Albert H. Hofstra and Douglas C. Kreiner
scandium (Sc), strontium (Sr), tantalum (Ta), tellurium (Te),
Abstract tin (Sn), titanium (Ti), tungsten (W), uranium (U), vanadium
(V), and zirconium (Zr).
To define and prioritize focus areas across the United In 2018, Congress allocated funds to the USGS Mineral
States with resource potential for 35 critical minerals in a Resources Program for the Earth Mapping Resources Initiative
few years’ time, the U.S Geological Survey Earth Mapping (Earth MRI), which is a partnership between the USGS, the
Resources Initiative (Earth MRI) required an efficient Association of American State Geologists, and other Federal,
approach to streamline workflow. A mineral systems approach State, and private-sector organizations. The goal of Earth MRI
based on current understanding of how ore deposits that is to generate maps and data that aid in increasing the domes-
contain critical minerals form and relate to broader geologic tic inventory of critical minerals (Day, 2019). To reach this
frameworks and the tectonic history of the Earth was used goal, focus areas with critical mineral resource potential must
to satisfy this Earth MRI need. This report describes the be defined and prioritized for new topographic, geologic, geo-
rationale for, and structure of, a table developed for Earth chemical, and geophysical mapping; and funds must be allo-
MRI that relates critical minerals and principal commodities cated to States and contractors to conduct the work. The new
to the deposit types and mineral systems in which they are maps of high priority focus areas are designed to (1) advance
concentrated. The hierarchical relationship between systems, understanding of, or “image,” the three-dimensional geologic
deposits, commodities, and critical minerals makes it possible framework, (2) stimulate exploration and development of
to define and prioritize each system-based focus area once for domestic resources of critical minerals, and (3) decrease the
all of the critical minerals that it may contain. This approach Nation’s reliance on foreign sources of critical minerals.
is advantageous because mineral systems are much larger During Phase 1, focus areas with potential for REE-
than individual ore deposits and they generally have geologic bearing deposit types were targeted and classified by geologic
features that can be “imaged” by the topographic, geologic, environment (Dicken and others, 2019; Hammarstrom and
geochemical, and geophysical mapping techniques deployed Dicken, 2019). In 2019, funds were allocated to map the pri-
by Earth MRI. oritized REE-focus areas and several studies were underway in
2020. During Phase 2, focus areas with potential for Al, C, Co,
Li, Nb, PGE, Sn, Ta, Ti, and W were targeted and classified
Background into mineral systems (explained in the “Mineral Systems” sec-
tion) that generate ore deposits containing the aforementioned
The President and Secretary of the Interior issued orders critical minerals. The plan for Phase 3 is to target and classify
(Executive Office of the President, 2017; U.S. Department of all or most of the remaining critical minerals (As, BaSO4, Be,
the Interior, 2017) that directed the U.S. Geological Survey Bi, CaF₂, Cr, Cs, Ga, Ge, He, Hf, In, KCl, Mg, Mn, Re, Rb,
(USGS) to develop a plan to improve the Nation’s understand- Sb, Sc, Sr, Te, U, V, and Zr).
ing of domestic critical mineral resources. In response, a list
of 35 critical minerals with a high risk for supply disruption
were identified by the National Minerals Information Center
(Fortier and others, 2018). The 35 critical minerals that were
Problem and Solution
identified are aluminum (Al), antimony (Sb), arsenic (As), To define and prioritize Earth MRI focus areas across the
barite (BaSO4), beryllium (Be), bismuth (Bi), cesium (Cs), United States for 35 critical minerals in a few years’ time, an
chromium (Cr), cobalt (Co), fluorspar (CaF₂), gallium (Ga), efficient method was needed that minimized the number of
germanium (Ge), graphite (C), hafnium (Hf), helium (He), focus areas and the number of times that each focus area was
indium (In), lithium (Li), magnesium (Mg), manganese (Mn), considered. Application of the commodity-based approach uti-
niobium (Nb), platinum group elements (PGEs), potash (KCl), lized for REE in Phase 1 to the remaining 34 critical minerals
rare earth elements (REE), rhenium (Re), rubidium (Rb), would be redundant and inefficient because, unlike REE and2 Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative
a few other exceptions (Al, BaSO4, C, PGE), critical minerals these components, produce mineral systems and ore deposits
generally do not constitute the major part of any single mineral of different types that are enriched in different principal com-
deposit. Instead, they are more commonly present as minor modities and byproducts, of which some are critical minerals.
constituents in deposits mined for principal commodities, such Mineral systems with genetically related ore deposits
as gold (Au), silver (Ag), lead (Pb), zinc (Zn), copper (Cu), generally form during an episode of magmatism, metamor-
molybdenum (Mo), nickel (Ni), iron (Fe), and phosphorus (P). phism, deformation, sedimentation, weathering, or erosion in
The solution to this problem, employed in Phases 2 and specific geotectonic settings (fig. 1). The geotectonic setting
3 of Earth MRI, was to take advantage of the hierarchical includes the actual tectonic configuration as well as aspects of
relationship that exists between mineral systems, ore deposits, crustal evolution and (or) climatic conditions that are required
principal commodities, and critical minerals (described in the for a system to produce significant deposits. If a setting lacks
“Table Rationale and Explanation” section) and define focus one or more key ingredients, such as dilatant structures,
areas that correspond, more or less, to the footprint of mineral enriched source rocks, an arid climate, or appropriate physical
systems, and then prioritize each system-based focus area once or chemical conditions, a mineral system may operate without
for the entire suite of critical minerals that it may contain. producing significant ore deposits. Systems generally require
An important advantage of this approach is that the scale of a trigger to get them started. Triggers can be sudden, such as
mineral systems is much larger than individual ore deposits volcanism above a mantle plume (for example, Ni-Cu-PGE
and they generally have key geologic features that can be deposits in a mafic magmatic system), or barely noticeable,
“imaged” by the Earth MRI mapping techniques described such as formation of a peneplain in a tropical climatic zone (for
previously. The number of focus areas can be further reduced example, bauxite deposits in a chemical weathering system).
by prioritizing only the largest and most prospective systems The vertical and lateral extents of mineral systems are
in the United States because, in most (but not all) cases, small quite variable. For example, a system may have large verti-
systems are unlikely to generate deposits that are large enough cal extents, as in porphyry Cu-Mo-Au systems that extend
to contain significant quantities of critical minerals. Another from the subduction zone to the surface (fig. 2C), or short
way to minimize the number of focus areas is to group mineral vertical extents, such as chemical weathering systems that
systems that occur in clusters or belts into one focus area. are restricted to the vadose zone between the surface and the
Similarly, because well-endowed mineral systems are known water table. Mineral systems can have large lateral extents, as
to form in specific tectonic settings and during specific time in basin brine path systems that extend from marine evaporite
periods of Earth history, such settings that have been identi- basins, across passive margins, to shelf-slope breaks where
fied in frontier areas or under cover can be designated as they discharge into the ocean (fig. 3). Other mineral systems
focus areas. can have small lateral extents, such as in carbonatites. Most
In the following sections, we describe mineral systems systems are spatially zoned such that deposits with different
and the rationale for, and structure of, the systems, deposits, commodities and critical minerals occur at different levels or
commodities, and critical minerals information compiled in in proximal to distal positions (for example, figs. 2A and 3).
table 1 (PDF file) and show how it can be used to streamline In some systems, critical minerals are enriched on the periph-
workflow for Earth MRI. ery of the system or deposit types within it, or they occur in
unconventional deposit types (for example, alunite altered
lithocaps). Some deposit types are mined for a single com-
modity, such as tungsten skarn deposits, whereas others are
Mineral Systems mined for several commodities, such as placer deposits mined
for Au, REE, Ti, and Zr-Hf. In some deposit types, the princi-
The mineral systems concept is based on current under- pal commodity is a critical mineral, but in most cases critical
standing of how ore deposits form and relate to broader minerals have been, or may only be, produced as byproducts
geologic frameworks and the tectonic history of the Earth of principal commodity deposits (Hayes and McCullough,
(for example, Wyborn and others, 1994; McCuaig and oth- 2018), such as REE from sedimentary phosphate deposits.
ers, 2010; Huston and others, 2016; and Geological Survey Detailed information on each system and deposit type is
of Western Australia, 2019). Mineral systems encompass provided in the references cited in table 1.
all of the components required to form ore deposits (fig. 1).
These components are (1) an optimum geotectonic setting,
(2) energy to drive the system (heat, gravity), (3) source rocks
for ligands and metals (igneous, metamorphic, or sedimentary Table Rationale and Explanation
rocks; preexisting mineralization), (4) a transport medium
(melts, aqueous fluids-liquids-vapors, petroleum-natural gas), Table 1 was populated with principal commodity and
(5) transport pathways (channels, permeable structures and critical mineral information gathered from ore deposit models
lithologies), (6) chemical and physical traps that concentrate published by the USGS, other government organizations, and
metals to ore grades (deposits), and (7) distal expressions scientific journals. This information was classified into mineral
(mineral, chemical, or thermal anomalies) that extend to the systems using the concept outlined in the “Mineral Systems”
limit of the system. In a given geotectonic setting, variations in section. This classification consisted of grouping deposit typesTable Rationale and Explanation 3
Components
Energy Ligand Source Transport Trap Outflow
Mineral System
(≤500 km) Deposit Halo
(≤10 km)
Deposit
(≤5 km)
INGREDIENTS
Model I
Metal
Source Model II
Ligand
Energy Source Residual
Model III
(Driving Force) Fluid Discharge
Transporting Fluid Trap Region
No Deposits
A.
Time
Global Craton Province District Deposit
B. Scale
Figure 1. Mineral system concepts. A, Modified from Knox-Robinson and Wyborn (1997).
B, Modified from Geoscience Australia (2019). (≤, less than or equal; km, kilometer)4 Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative
High-sulfidation dissem.
A. Au ±Ag ±Cu
Alunite Intermediate
Al K Ga Sulfidation
Au-Ag
Mn As Sb
High-sulfidation Carbonate replacement
Base of Cu-Au, ±Ag Zn-Pb-Ag ±Au ±Cu
lithocap Te Bi Ga Ge In Mn
Au/Zn-Pb
skarn
Vein Distal-
Zn-Cu-Pb- dissem.
Ag ±Au Marble Au-As
front ±Sb ±Hg
Porphry Cu
±Au ±Mo Cu-Au skarn
Te In PGE Re W skarn
Greisen
1 km W-Sn ±Be ±Li
Lithocap
B. Paleosurface
Volcanic Multiphase
edifice stock Subvolcanic basement
Composite
pluton
5 km
C.
Figure 2. Schematic cross sections of a porphyry copper (Cu)-molybdenum (Mo)-gold (Au) system (with critical minerals in
blue) at various scales. A and B, Modified from Sillitoe (2010). C, Modified from Tosdal and others (2009). (Ag, silver; Al, aluminum;
As, arsenic; Be, beryllium; Bi, bismuth; Co, cobalt; dissem., disseminated; Ga, gallium; Hg, mercury; In, indium; K, potassium; km,
kilometer; Li, lithium; MASH, melting, assimilation, and homogenization; Mn, manganese; Pb, lead; PGE, platinum group elements;
Re, rhenium; Sb, antimony; SLM, subcontinental lithospheric mantle; Sn, tin; Te, tellurium; W, tungsten; Zn, zinc)Fluid source – Large shallow platform ( > 105 km2)
Seawater evaporation with dolomite, salt, gypsum,
and residual brine with K, Sr, Mg, Rb, Cs
Distal expressions -
Metalliferous black shale U V PGE Re
Fe-Mn±Co, barite Sr, phosphate REE U
Hydrothermal dolomite Rift sag sequence (1-4 km) – Limestone,
MVT and Irish-type deposits shale, calcareous shale, siltstone
Dolostone K-Na alteration
Metal traps - Anoxic/Euxinic
10 Kilometers
bathymetric lows. Black shales >1% TOC Sedex
deposits Fluid drive – Density-driven brine reflux with
dolomitization and K-Na alteration along
migration pathways
K-Na alteration
Li-brines Rift fill sequence (>3 km) – Coarse- to fine-grained
oxidized continental clastic rocks, ± evaporites,
Alkali alteration commonly with felsic and mafic volcanics, dikes and sills
Fe/Mn carbonate
Plumbing system – Long-lived synsedimentary basin faults
evidenced by facies, isopachs, breccias, slumps
0 100 Kilometers
0 100 Miles
(Pb ±Bi-Sb, Zn ±Ga-Ge-In-Bi, Cu ±Co)
Table Rationale and Explanation 5
Figure 3. Schematic model of a basin brine path system (with critical minerals in blue), modified from Emsbo, 2009. (>, greater than; %, percent; Ba, barium; Bi, bismuth;
Co, cobalt; Cs, cesium; Cu, copper; Fe, iron; Ga, gallium; Ge, germanium; In, indium; K, potassium; km, kilometer; km2, square kilometer; Li, lithium; Mg, magnesium; Mn,
manganese; MVT, Mississippi Valley-type; Na, sodium; Pb, lead; PGE, platinum group elements; PO4, phosphate; Rb, rubidium; Re, rhenium; REE, rare earth elements; U,
uranium; V, vanadium; Sb, antimony; Sr, strontium; TOC, total organic carbon; Zn, zinc)6 Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative
that share a fundamental genetic relationship to geologic con- contain a similar assortment of principal commodities and criti-
trols that are characteristic of each system type. Thus, if one cal minerals whereas those with distinct principal commodities
part (for example, deposit type) of a system is identified, then and critical minerals were split out. The fourth column is a list
the other parts (for example, other deposit types) of the system of “Principal commodities” that generally are produced from,
may be present nearby. or explored for, in the deposit type. These are the commodities
As table 1 was being constructed, it became clear that it that govern the economics of mining and mineral processing.
could be simplified and made more useful for Earth MRI by (1) The fifth column is a list of “Critical minerals.” Those that have
grouping deposit types with similar mineral assemblages that actually been produced from the deposit type are highlighted in
contain similar element suites, and (or) (2) splitting out deposit bold type (for example, REE), whereas those that are enriched
types with distinct mineralogies and elements. This decision in the deposit type, but have not yet been produced, are listed in
was based on the common mineral associations that occur in italics (for example, PGE). Critical minerals that are principal
certain deposit types and the typical element substitutions that commodities, are listed in both columns. The sixth column is
occur in each mineral. For example, in porphyry Cu-Mo-Au “Reference(s),” which cites publications that contain detailed
systems (fig. 2A–B), polymetallic skarn, replacement, vein, descriptions of the system and deposit types upon which the
and intermediate sulfidation (SRVIS) deposits all contain entries in table 1 are based.
various proportions of Cu-, Zn-, and Pb-sulfides and As- and
Sb-sulfosalts with variable proportions of the same principal
commodities (Cu, Zn, Pb, Ag, Au) and critical minerals (Ge, Table Use
Ga, In, Bi, Sb, As, W, Te). Thus, an overarching deposit name
The hierarchical relationship between systems, deposits,
was devised to encompass them, “polymetallic SRVIS.” In
commodities, and critical minerals in table 1 can be used to
an analogous way, Cu-sulfides in porphyry and skarn copper
help define and prioritize Earth MRI focus areas for mapping
deposits typically contain PGE, Te, and Bi; molybdenite in
projects in four ways.
porphyry and skarn molybdenum deposits contains Re; pyrite
First, if any part of a mineral system has been recognized
in distal disseminated silver-gold deposits contains As and Sb;
by previous work, table 1 can be used to deduce the assortment
and alunite in lithocap deposits contains Al, K, and Ga. Placers
of deposit types, principal commodities, and critical minerals
are more complex because the assemblage of ore minerals
that may be present in adjacent areas and under cover. Because
that they contain reflects the assemblage of source rocks and
information generally exists on the principal commodities and
mineralization exposed in the catchment area. Consequently, it
deposit types that are present in well-explored areas with a his-
is important to understand that the distinctions made in table 1
tory of mining, table 1 can be used to infer the system type(s)
are idealized and that in nature the deposit types grade into, or
and the critical minerals that may be present in mine waste,
overlap with, one another. Nevertheless, the deposit groupings
unmined resources, concealed deposit types under cover, or in
and distinctions can be used to identify the parts or aspects of a
deposit types that were removed by erosion. In areas with his-
mineral system that are likely to be enriched in specific princi-
torical mining and exploration, these inferences have a higher
pal commodities and critical minerals.
degree of certainty because the known deposit types confirm
that a mineral system actually operated in the area. The deposit
Table Structure types recognized at or near the surface also provide an indica-
tion of the level of exposure or tilting of the system.
The table consists of six columns (with headers in bold Second, for system-based focus areas of the same type (for
type). The first is the “System name.” In some cases, an estab- example, porphry Cu-Mo-Au), the attributes of each area can
lished name was used, for example, “Placer.” In other cases, be compared to identify those that are well endowed and (or)
a name was selected that emphasizes an aspect of the system would benefit the most from Earth MRI mapping techniques.
that is characteristic of, and distinct from, the other systems, Third, in some parts of the country, systems of differ-
for example, “Chemical Weathering.” One system was named ent types and ages occur in the same geographic area, such
after the principal deposit type within it, namely “Porphyry that the system-based focused areas overlap. These areas are
Cu-Mo-Au.” In this case, it is important to realize that porphyry highly prospective and may benefit the most from Earth MRI
Cu-Mo-Au systems are much larger than porphyry Cu-Mo-Au mapping efforts.
deposits and encompass key aspects of the tectonic framework Fourth, in frontier areas (for example, Alaska) or areas
and all of the deposit types that occur within the system, as with extensive cover (for example, U.S. mid-continent), if a
shown in figure 2. The second column is a brief “Synopsis” that geotectonic setting, or terrane, is recognized that is known to
provides information on the geotectonic setting of the system host mineral systems of a given type elsewhere in the world
and a description of how it operates to form ore deposits con- (for example, Mesoproterozoic magmatic provinces), table 1
taining various principal commodities and critical minerals. The can be used to infer the deposit types, principal commodities,
third column is “Deposit types.” As described in the previous and critical minerals that may be present. In this case, Earth
section, in some cases, different deposit types were grouped MRI maps of such terranes may detect evidence of mineral
together under an overarching deposit name because they systems and lead to new discoveries.Table 1. Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative.
[±, present (absent); —, not applicable; ?, maybe; Ag, silver; Al, aluminum; As, arsenic; Au, gold; B, boron; Ba, barium; Be, beryllium; Bi, bismuth; Br, bromine; Ca, calcium; Cd, cadmium; Co, cobalt; CO2,
carbon dioxide; Cs, cesium; Cr, chromium; Cu, copper; F, fluorine; Fe, iron; Ga, gallium; Ge, germanium; Hf, hafnium; Hg, mercury; I, iodine; In, indium; IOA, iron oxide-apatite; IOCG, iron oxide-copper-gold;
IS, intermediate sulfidation; K, potassium; LCT, lithium-cesium-tantalum; Li, lithium; Mg, magnesium; Mn, manganese; Mo, molybdenum; Na, sodium; Nb, niobium; Ni, nickel; NYF, niobium-yttrium-fluorine;
P, phosphorus; Pb, lead; PGE, platinum group elements; R, replacement; Rb, rubidium; Re, rhenium; REE, rare earth elements; S, skarn; Sb, antimony; Sc, scandium; SE, selenium; Sn, tin; Sr, strontium; Ta, tanta-
lum; Te, tellurium; Th, thorium; Ti, titanium; Tl, thallium; U, uranium; V, vanadium (in “Commodity” column; V, vein (in “Deposit type” column); W, tungsten; Y, yttrium; Zn, zinc; Zr, zirconium]
System name Synopsis Deposit types Principal commodities Critical minerals1 Reference(s)
Placer (riverine-marine, Placer systems operate in drainage Gold Au — Levson, 1995; Van
residual-eluvial-alluvial- basins and along shorelines where Uraninite, autunite-group minerals U U Gosen and others,
shoreline, paleo) there is either topographic relief and 2014; Sengupta
PGE PGE PGE
gravity-driven turbulent flow of sur- and Van Gosen,
face water or tidal and wind-driven Cassiterite Sn Sn 2016; Jones and
wave action. Placer systems con- Wolframite/scheelite W W others, 2017
centrate insoluble resistate minerals
Barite Barite Barite
liberated from various rock types
and mineral occurrences by the Fluorite Fluorite Fluorite
chemical breakdown and winnowing Monazite/xenotime REE, Y, Th REE
away of enclosing minerals by the Columbite/tantalite Nb, Ta Nb, Ta, Mn
movement of water. The distribu-
tion of insoluble resistate minerals is Zircon Zr, Hf Zr, Hf
controlled by their size, density, and Ilmenite/rutile/leucoxene Ti Ti
the turbulence of fluid flow. Diamond Diamond gems and abrasive —
Sapphire Sapphire gems —
Garnet Garnet gems and abrasive —
Chemical weathering (un- Chemical weathering systems operate Nickel-cobalt laterite Ni, Co Co, Sc Marsh and others,
saturated zone, in situ) in stable areas of low to moder- Bauxite Al Al, Ga, REE 2013; Foley and
ate relief with sufficient rainfall to Ayuso, 2015;
chemically dissolve and concentrate Clay Kaolin Ga, Li, REE Bruneton and
elements present in various rock Carbonatite laterite Nb, REE Nb, REE Cuney, 2016;
types and mineral occurrences by Regolith (Ion adsorption) REE REE REE Sanematsu and
the downward percolation of surface Watanabe, 2016
Table Rationale and Explanation 7
Surficial uranium U U
water in the unsaturated zone.
Chemical gradients cause differ- Supergene (and laterite) gold Au —
ent elements to be concentrated at Supergene silver Ag ?
different positions in the weather- Supergene lead Pb ?
ing profile and at the water table.
Bauxite, Ni-laterite, and carbonatite Supergene zinc Zn ?Ge, Ga, In?
laterite are restricted to tropical Supergene (and exotic) copper Cu ?Te, Bi?
climatic zones; others form in tem- Supergene cobalt Co Co
perate and arid climates.
Supergene PGE PGE PGE
Supergene manganese Mn Mn, Co
Supergene iron Fe MnTable 1. Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative. —Continued
8 Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative
[±, present (absent); —, not applicable; ?, maybe; Ag, silver; Al, aluminum; As, arsenic; Au, gold; B, boron; Ba, barium; Be, beryllium; Bi, bismuth; Br, bromine; Ca, calcium; Cd, cadmium; Co, cobalt; CO2,
carbon dioxide; Cs, cesium; Cr, chromium; Cu, copper; F, fluorine; Fe, iron; Ga, gallium; Ge, germanium; Hf, hafnium; Hg, mercury; I, iodine; In, indium; IS, intermediate sulfidation; K, potassium; LCT,
lithium-cesium-tantalum; Li, lithium; Mg, magnesium; Mn, manganese; Mo, molybdenum; Na, sodium; Nb, niobium; Ni, nickel; NYF, niobium-yttrium-fluorine; P, phosphorus; Pb, lead; PGE, platinum group
elements; R, replacement; Rb, rubidium; Re, rhenium; REE, rare earth elements; S, skarn; Sb, antimony; Sc, scandium; SE, selenium; Sn, tin; Sr, strontium; Ta, tantalum; Te, tellurium; Th, thorium; Ti, titanium;
Tl, thallium; U, uranium; V, vanadium; W, tungsten; Y, yttrium; Zn, zinc; Zr, zirconium]
System name Synopsis Deposit types Principal commodities Critical minerals1 Reference(s)
Meteoric recharge Meteoric recharge systems operate Sandstone uranium U, V U, V, Re, Sc, Skirrow and others,
where oxidized meteoric ground- REE, Co, PGE 2009; Breit, 2016;
water displaces reduced connate Calcrete uranium U, V U, V, Sr Bruneton and
water in sandstone aquifers that Cuney, 2016; Hall
often contain volcanic ash or where and others, 2019
such groundwater evaporates at the
surface. As oxidized water descends
through sandstone aquifers, it
scavenges uranium and other ele-
ments from detrital minerals and (or)
volcanic glass. Uranium and other
elements precipitate at the redox
front with reduced connate water,
on carbonaceous material in the
aquifers, or at the surface in calcrete
by evaporation.
Lacustrine evaporite Lacustrine evaporite systems operate Trona Soda ash (Na2CO3) — Dyni, 1991;
in closed drainage basins in arid to Gypsum Gypsum (CaSO4•2H2O) — Sheppard,
hyperarid climatic zones. Elements 1991a,b;
Salt Salt (NaCl) —
present in meteoric surface, ground, Williams-Stroud,
and geothermal recharge water are Potash Potash (KCl) Potash 1991; Orris,
concentrated by evaporation. As Carnallite Carnellite (KMgCl3•6H2O) Potash, Mg 1995; Warren,
salinity increases, evaporite minerals 2010; Bradley
Borate Borax, boric Acid Li
typically precipitate in the follow- and others, 2013;
ing sequence: gypsum or anhydrite, Nitrate [Na, K, Ca, Mg][NO3 nitrate, Mg Hofstra and
halite, sylvite, carnallite, borate. IO3 iodate, BO3 borate] others, 2013b;
Nitrates are concentrated in basins Residual brine Salt, potash, borax, boric acid, Potash, Li, Mn, Munk and others,
that accumulate sea spray. Residual soda ash, sodium sulfate, Li, Rb, Cs, Mg, 2016; Bradley and
brines enriched in lithium and other Rb, Cs, Mg, Mn, Sr, Br, I, Sr, W others, 2017b
elements often accumulate in aqui- W, Zn
fers below dry lake beds. Li-clay Lithium clay Li Li
and Li-zeolite deposits form where
residual brine reacts with lake sedi- Lithium-boron zeolite Zeolite, B, Li Li
ment, ash layers, or volcanic rocks.Table 1. Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative. —Continued
[±, present (absent); —, not applicable; ?, maybe; Ag, silver; Al, aluminum; As, arsenic; Au, gold; B, boron; Ba, barium; Be, beryllium; Bi, bismuth; Br, bromine; Ca, calcium; Cd, cadmium; Co, cobalt; CO2,
carbon dioxide; Cs, cesium; Cr, chromium; Cu, copper; F, fluorine; Fe, iron; Ga, gallium; Ge, germanium; Hf, hafnium; Hg, mercury; I, iodine; In, indium; IS, intermediate sulfidation; K, potassium; LCT,
lithium-cesium-tantalum; Li, lithium; Mg, magnesium; Mn, manganese; Mo, molybdenum; Na, sodium; Nb, niobium; Ni, nickel; NYF, niobium-yttrium-fluorine; P, phosphorus; Pb, lead; PGE, platinum group
elements; R, replacement; Rb, rubidium; Re, rhenium; REE, rare earth elements; S, skarn; Sb, antimony; Sc, scandium; SE, selenium; Sn, tin; Sr, strontium; Ta, tantalum; Te, tellurium; Th, thorium; Ti, titanium;
Tl, thallium; U, uranium; V, vanadium; W, tungsten; Y, yttrium; Zn, zinc; Zr, zirconium]
System name Synopsis Deposit types Principal commodities Critical minerals1 Reference(s)
Marine evaporite Marine evaporite systems operate in Gypsum Gypsum (CaSO4•2H2O) — Raup 1991a, b;
shallow restricted epicontinental Salt Salt (NaCl) — Warren, 2010
basins in arid to hyperarid climatic
Potash Potash (KCl) Potash
zones. Elements present in seawater
are concentrated by evaporation. As Dissolution brine Petroleum, salt (NaCl) —
salinity increases, evaporite minerals
typically precipitate in the follow-
ing sequence: gypsum or anhydrite,
halite, sylvite. Residual basin brines
are enriched in conserved elements,
such as Mg and Li. Incursion of
freshwater or seawater can produce
halite dissolution brines.
Basin brine path Basin brine path systems emanate from Basin brine Petroleum, salt, potash, Li, Rb, Potash, Li, Rb, Cox and Singer,
marine evaporite basins and extend Cs, Mg, Sr, Br, I, Zn Cs, Mg, Sr 2007; Skirrow
downward and laterally through Hydrothermal dolomite Building stone, aggregate Mg and others, 2009;
permeable strata to discharge points Alpine, 2010;
Zinc-lead (MVT and sedex) Zn, Pb, Ag, Cu, Co Sn, Ge, Co, Ga, In
in the ocean. Basin brines evolve Leach and others,
to become ore fluids by scaveng- Copper (sed-hosted and replace- Cu, Co, Ag, Pb, Zn Co, PGE, Re, 2010; Hayes and
ing metals from various rock types ment) Ge, Ga, V, U others, 2015;
along gravity-driven flow paths. The Uranium (unconformity and brec- U, V, Cu, Co, Mo, Re, Se, Sc, U, V, Re, Sc, Emsbo and others,
mineralogy of the aquifers controls cia pipe) REE REE, Co 2016a; Marsh
the redox and sulfidation state of and others, 2016;
Barite (replacement and bedded) Barite (witherite) Barite
the brine and the suite of elements Johnson and
that can be scavenged. Cu- and Strontium (replacement and bed- Sr (celestite, strontianite) Sr others, 2017;
Table Rationale and Explanation
Pb-Zn sulfide deposits form where ded) Manning and
oxidized brines encounter reduced Emsbo, 2018
S. Unconformity U deposits form
where oxidized brines are reduced.
Ba and Sr deposits form where
reduced brines encounter marine
sulfate or carbonate.
9Table 1. Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative. —Continued
10
[±, present (absent); —, not applicable; ?, maybe; Ag, silver; Al, aluminum; As, arsenic; Au, gold; B, boron; Ba, barium; Be, beryllium; Bi, bismuth; Br, bromine; Ca, calcium; Cd, cadmium; Co, cobalt; CO2,
carbon dioxide; Cs, cesium; Cr, chromium; Cu, copper; F, fluorine; Fe, iron; Ga, gallium; Ge, germanium; Hf, hafnium; Hg, mercury; I, iodine; In, indium; IS, intermediate sulfidation; K, potassium; LCT,
Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative
lithium-cesium-tantalum; Li, lithium; Mg, magnesium; Mn, manganese; Mo, molybdenum; Na, sodium; Nb, niobium; Ni, nickel; NYF, niobium-yttrium-fluorine; P, phosphorus; Pb, lead; PGE, platinum group
elements; R, replacement; Rb, rubidium; Re, rhenium; REE, rare earth elements; S, skarn; Sb, antimony; Sc, scandium; SE, selenium; Sn, tin; Sr, strontium; Ta, tantalum; Te, tellurium; Th, thorium; Ti, titanium;
Tl, thallium; U, uranium; V, vanadium; W, tungsten; Y, yttrium; Zn, zinc; Zr, zirconium]
System name Synopsis Deposit types Principal commodities Critical minerals1 Reference(s)
Marine chemocline (bath- Marine chemocline systems operate Black shale Stone coal, petroleum, V, Ni, V, Re, PGE Lefebure and
tub rim) where basin brines discharge into Mo, Au, PGE Coveney, 1995;
the ocean. Consequent increases in Phosphate Phosphate fertilizer F, REE, U Force and others,
bioproductivity produce metallifer- 1999; Emsbo,
Iron-manganese Fe, Mn, Co Mn, Co
ous black shales. Changes in ocean 2000; Emsbo
chemistry (oceanic anoxic events) Superior iron Fe — and others, 2015,
and development of chemoclines 2016b; Cannon
result in chemical sedimentation of and others, 2017
phosphate and Mn and Fe carbon-
ates and oxides.
Hybrid magmatic REE/ This hybrid system operates where Fluorspar Fluorite Fluorite, barite, Plumlee and others,
basin brine path CO2- and HF-bearing magmatic vol- REE, Ti, Nb, Be 1995; Denny and
atiles condense into basinal brines others, 2015,
that replace carbonate with fluorspar 2016; Hayes and
± barite, REE, Ti, Nb, and Be as others, 2017
in the Illinois-Kentucky Fluorspar
District and Hicks Dome.
Arsenide Arsenide systems form in continental Five element veins Ag, As, Co, Ni, Bi, U, Sb Co, Bi, U, As, Sb Kissin, 1992, Markl
rifts where deep-seated, oxidized, and others, 2016;
metal-rich, metamorphic basement Burisch and
brines ascend to shallow levels. others, 2017;
Native elements (Ag, Bi, As), Ni-, Scharrer and
Co- and Fe-mono-, di- and sulf- others, 2019
arsenides precipitate by reduction as
hydrocarbons, graphite, or sulfide
minerals are oxidized to form car-
bonates and barite.Table 1. Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative. —Continued
[±, present (absent); —, not applicable; ?, maybe; Ag, silver; Al, aluminum; As, arsenic; Au, gold; B, boron; Ba, barium; Be, beryllium; Bi, bismuth; Br, bromine; Ca, calcium; Cd, cadmium; Co, cobalt; CO2,
carbon dioxide; Cs, cesium; Cr, chromium; Cu, copper; F, fluorine; Fe, iron; Ga, gallium; Ge, germanium; Hf, hafnium; Hg, mercury; I, iodine; In, indium; IS, intermediate sulfidation; K, potassium; LCT,
lithium-cesium-tantalum; Li, lithium; Mg, magnesium; Mn, manganese; Mo, molybdenum; Na, sodium; Nb, niobium; Ni, nickel; NYF, niobium-yttrium-fluorine; P, phosphorus; Pb, lead; PGE, platinum group
elements; R, replacement; Rb, rubidium; Re, rhenium; REE, rare earth elements; S, skarn; Sb, antimony; Sc, scandium; SE, selenium; Sn, tin; Sr, strontium; Ta, tantalum; Te, tellurium; Th, thorium; Ti, titanium;
Tl, thallium; U, uranium; V, vanadium; W, tungsten; Y, yttrium; Zn, zinc; Zr, zirconium]
System name Synopsis Deposit types Principal commodities Critical minerals1 Reference(s)
Volcanogenic seafloor Volcanogenic seafloor systems are Copper-zinc sulfide Cu, Zn Co, Bi, Te, In, Sn, Levson, 1995;
driven by igneous activity along Ge, Ga, Sb Shanks and
spreading centers, back-arc basins Zinc-copper sulfide Zn, Cu Ge, Ga, Sb, Co, Thurston, 2012;
and magmatic arcs. In spread- Bi, Te, In, Sn Monecke and
ing centers and back-arc basins, others, 2016;
Polymetallic sulfide Cu, Zn, Pb, Ag, Au Sn, Bi, Te, In, Ge,
seawater evolves to become an ore Cannon and
Ga, Sb, As
fluid by convection through hot others, 2017
volcanic rocks. In magmatic arcs, Barite Barite Barite
ore fluids exsolved from subvolcanic Manganese oxide (layers, crusts, Mn, Fe, Ni Mn, Co, Ge
intrusions may mix with convecting nodules)
seawater. Ore deposits form where
Algoma iron Fe ?
hot reduced ore fluids vent into cool
oxygenated seawater. Sulfides and
sulfates precipitate in or near vents.
Mn and Fe precipitate at chemo-
clines over wide areas in basins with
seafloor hydrothermal activity .
Orogenic Metamorphic dewatering of sulfidic Gold Au, Ag W, Te, As, Sb Groves and others,
volcanic and (or) sulfidic, carbona- Antimony Sb, Au, Ag Sb 1998; Gray and
ceous, and (or) calcareous siliciclas- Bailey, 2003;
Mercury Hg, Sb Sb
tic sequences during exhumation Goldfarb and
with fluid flow along dilatant struc- Graphite Graphite (lump) Graphite (lump) others, 2005,
tures. Iron minerals in host rocks are 2016; Luque and
often sulfidized. Metavolcanic host others, 2014
Table Rationale and Explanation
rocks often contain volcanogenic
seafloor sulfide deposits.
Coeur d’Alene-type Metamorphic dewatering of moder- Polymetallic sulfide Ag, Pb, Zn, Cu Sb, Co, Ge, Ga, Leach and others,
ately oxidized siliciclastic se- In 1988, 1998;
quences during exhumation with Antimony Sb Sb Beaudoin and
fluid flow along dilatant structures. Sangster, 1992,
Metasedimentary host rocks may 1995; Balistrieri
contain basin brine path Pb-Zn and and others, 2002;
Cu±Co deposits. Hofstra and others,
2013a; Seal and
others, 2017
11Table 1. Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative. —Continued
12
[±, present (absent); —, not applicable; ?, maybe; Ag, silver; Al, aluminum; As, arsenic; Au, gold; B, boron; Ba, barium; Be, beryllium; Bi, bismuth; Br, bromine; Ca, calcium; Cd, cadmium; Co, cobalt; CO2,
carbon dioxide; Cs, cesium; Cr, chromium; Cu, copper; F, fluorine; Fe, iron; Ga, gallium; Ge, germanium; Hf, hafnium; Hg, mercury; I, iodine; In, indium; IS, intermediate sulfidation; K, potassium; LCT,
Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative
lithium-cesium-tantalum; Li, lithium; Mg, magnesium; Mn, manganese; Mo, molybdenum; Na, sodium; Nb, niobium; Ni, nickel; NYF, niobium-yttrium-fluorine; P, phosphorus; Pb, lead; PGE, platinum group
elements; R, replacement; Rb, rubidium; Re, rhenium; REE, rare earth elements; S, skarn; Sb, antimony; Sc, scandium; SE, selenium; Sn, tin; Sr, strontium; Ta, tantalum; Te, tellurium; Th, thorium; Ti, titanium;
Tl, thallium; U, uranium; V, vanadium; W, tungsten; Y, yttrium; Zn, zinc; Zr, zirconium]
System name Synopsis Deposit types Principal commodities Critical minerals1 Reference(s)
Metamorphic Metamorphic systems recrystallize Graphite (coal or carbonaceous Graphite (amorphous and flake) Graphite (amor- Sutphin, 1991a,b,c;
rocks containing organic carbon or sed) phous and Luque and others,
REE phosphate minerals. flake) 2014; McKin-
Gneiss REE (monazite, xenotime) Th, U, REE, Y REE, U ney and others,
2015; Sutherland
and Cola, 2016
Robinson and
others, 2017
Porphyry Cu-Mo-Au Porphyry copper-molybdenum-gold Greisen Mo, W, Sn W, Sn Seedorff and others,
systems operate in oceanic and S-R-V tungsten W W, Bi, Mn 2005; John and
continental magmatic arcs with others, 2010,
Porphyry/skarn molybdenum Mo, W, Sn W, Re, Bi
calc-alkaline compositions. Aqueous 2017; Sillitoe,
supercritical fluids exsolved from Porphyry/skarn copper Cu, Au, Ag, Mo PGE, Te, Re, Co, 2010; Taylor and
felsic plutons and the apices of Bi, U others, 2012; John
subvolcanic stocks form a variety of Skarn iron Fe, Cu Ge and Taylor, 2016;
deposit types as they move upward London, 2016
Polymetallic sulfide S-R-V-IS Cu, Zn, Cd, Pb, Ag, Au Mn, Ge, Ga, In,
and outward, split into liquid and
Bi, Sb, As,
vapor, react with country rocks, and
W, Te
mix with groundwater. The broad
spectrum of deposit types results Distal disseminated silver-gold Ag, Au Sb, As
from the large thermal and chemical High-sulfidation gold-silver Cu, Ag, Au As, Sb, Te, Bi, Sn,
gradients in these systems. Ga
Lithocap alunite Al, K2SO4 Al, K2SO4, Ga
Lithocap kaolinite Kaolin Ga
Alkalic porphyry Alkalic porphyry systems form in oce- Greisen Mo, Bi Bi Jensen and Barton,
anic and continental magmatic arcs S-R-V Tungsten W W, Bi, Mn 2000; Kelley and
and in continental rifts by similar Spry, 2016
Porphyry/skarn copper-gold Cu, Mo, Au PGE, Te, Bi
processes from fluids exsolved from
more fractionated alkalic plutons Polymetallic sulfide S-R-V-IS Au, Ag, Pb, Zn, Cu Ge, Ga, In, Bi, Te
and stocks. Resulting ore deposits Distal disseminated silver-gold Ag, Au Sb, As
tend to be more enriched in Au, Te,
High sulfidation Cu, Ag, Au Te, Bi, As, Sb
Bi, and V.
Low sulfidation Au Te, Bi, V, F
Lithocap alunite? Al, K2SO4 Al, K2SO4, Ga
Lithocap kaolinite? Kaolin GaTable 1. Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative. —Continued
[±, present (absent); —, not applicable; ?, maybe; Ag, silver; Al, aluminum; As, arsenic; Au, gold; B, boron; Ba, barium; Be, beryllium; Bi, bismuth; Br, bromine; Ca, calcium; Cd, cadmium; Co, cobalt; CO2,
carbon dioxide; Cs, cesium; Cr, chromium; Cu, copper; F, fluorine; Fe, iron; Ga, gallium; Ge, germanium; Hf, hafnium; Hg, mercury; I, iodine; In, indium; IS, intermediate sulfidation; K, potassium; LCT,
lithium-cesium-tantalum; Li, lithium; Mg, magnesium; Mn, manganese; Mo, molybdenum; Na, sodium; Nb, niobium; Ni, nickel; NYF, niobium-yttrium-fluorine; P, phosphorus; Pb, lead; PGE, platinum group
elements; R, replacement; Rb, rubidium; Re, rhenium; REE, rare earth elements; S, skarn; Sb, antimony; Sc, scandium; SE, selenium; Sn, tin; Sr, strontium; Ta, tantalum; Te, tellurium; Th, thorium; Ti, titanium;
Tl, thallium; U, uranium; V, vanadium; W, tungsten; Y, yttrium; Zn, zinc; Zr, zirconium]
System name Synopsis Deposit types Principal commodities Critical minerals1 Reference(s)
Porphyry Sn (granite- Granite-related porphyry Sn systems Pegmatite LCT Li-Cs-Ta Li, Cs, Ta, Nb, Panteleyev, 1996;
related) form in back-arc or hinterland Sn, Be Sillitoe and
settings by similar processes from Greisen Sn, W, Be Sn, W, Be others, 1998;
fluids exsolved from more crustally Černý and Ercit,
Porphyry/skarn Sn, W, Be Sn, W, Be
contaminated S-type peraluminous 2005; Martin and
plutons and stocks. At deep levels, Polymetallic sulfide S-R-V-IS Cu, Zn, Pb, Ag, Au Sn, Mn, Ge, Ga, De Vito, 2005;
LCT pegmatites emanate from In, Bi, Sb, As London, 2008,
plutons. Resulting ore deposits tend Distal disseminated silver-gold Ag, Au Sb, As 2016; Bradley
to be Cu and Mo poor and enriched and others,
High sulfidation Cu, Ag, Au Sn, Sb, As, Te, Bi
in Li, Cs, Ta, Nb, Sn, W, Ag, Sb, 2017a; Kamilli
and In. Lithocap alunite Al, K2SO4 Al, K2SO4, Ga and others, 2017;
Lithocap kaolinite Kaolin Ga Hulsbosch, 2019
Reduced intrusion-related Reduced intrusion-related systems Gold Au, Ag Te, Bi, Sb, As Hart, 2007; Nutt and
form in continental magmatic arcs Skarn copper-molybdenum- W, Mo, Cu, Au, Ag W, Te, Bi, Re Hofstra, 2007;
by similar processes from fluids tungsten Luque and others,
exsolved from calc-alkaline plutons 2014
Polymetallic sulfide S-R-V-IS Au, Ag, Pb, Zn, Cu Mn, Ge, Ga, In,
and stocks that assimilated car-
Bi, Sb, As
bonaceous pyritic country rocks.
Resulting ore deposits tend to be Distal disseminated silver-gold Ag, Au Te, Bi, Sb, As
poor in Cu, Mo, and Sn and enriched Intermediate sulfidation Au, Ag, Pb, Zn, Cu Mn, Ge, Ga, In,
in W, Au, Ag, Te, Bi, Sb, and As. Bi, Sb, As
Graphite Graphite (lump) Graphite (lump)
Table Rationale and Explanation
13Table 1. Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative. —Continued
14
[±, present (absent); —, not applicable; ?, maybe; Ag, silver; Al, aluminum; As, arsenic; Au, gold; B, boron; Ba, barium; Be, beryllium; Bi, bismuth; Br, bromine; Ca, calcium; Cd, cadmium; Co, cobalt; CO2,
carbon dioxide; Cs, cesium; Cr, chromium; Cu, copper; F, fluorine; Fe, iron; Ga, gallium; Ge, germanium; Hf, hafnium; Hg, mercury; I, iodine; In, indium; IS, intermediate sulfidation; K, potassium; LCT,
Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative
lithium-cesium-tantalum; Li, lithium; Mg, magnesium; Mn, manganese; Mo, molybdenum; Na, sodium; Nb, niobium; Ni, nickel; NYF, niobium-yttrium-fluorine; P, phosphorus; Pb, lead; PGE, platinum group
elements; R, replacement; Rb, rubidium; Re, rhenium; REE, rare earth elements; S, skarn; Sb, antimony; Sc, scandium; SE, selenium; Sn, tin; Sr, strontium; Ta, tantalum; Te, tellurium; Th, thorium; Ti, titanium;
Tl, thallium; U, uranium; V, vanadium; W, tungsten; Y, yttrium; Zn, zinc; Zr, zirconium]
System name Synopsis Deposit types Principal commodities Critical minerals1 Reference(s)
Carlin-type Carlin-type systems occur in continen- Gold Au, Ag, Hg As, Sb Hofstra and Cline,
tal magmatic arcs but are remote Antimony Sb Sb 2000; Goldfarb
from subjacent stocks and plutons. and others, 2016;
Arsenic-thallium-mercury As, Tl, Hg As
Consequently, ore fluids consist Muntean, 2018
largely of meteoric water contain-
ing volatiles discharged from deep
intrusions. Ore fluids scavenge
elements from carbonaceous pyritic
sedimentary rocks as they convect
through them. Gold ore containing
disseminated pyrite forms where
acidic reduced fluids dissolve carbon-
ate and sulfidize Fe-bearing minerals
in host rocks. As, Hg, and Tl minerals
precipitate by cooling. Stibnite pre-
cipitates with quartz by cooling from
Au-, As-, Hg-, and Tl-depleted fluids.
Climax-type Climax-type systems occur in conti- Pegmatite NYF Nb, Y, F, Be Nb, Ta, Be Černý and Ercit,
nental rifts with hydrous bimodal Greisen Mo, W, Sn W, Sn, Bi 2005; Martin and
magmatism. Aqueous supercritical De Vito, 2005;
Porphyry molybdenum Mo, W, Sn W, Sn, Re
fluids exsolved from A-type topaz London, 2008,
rhyolite plutons, and the apices of Skarn molybdenum Mo, W, Sn W, Sn 2016; Ludington
subvolcanic stocks form a variety of Polymetallic sulfide S-R-V-IS Cu, Zn, Pb, Ag, Au Mn, Ge, Ga, In, and Plumlee,
deposit types as they move upward Bi, Sb, As 2009; Breit
and outward, split into liquid and and Hall, 2011;
Distal disseminated silver-gold Ag, Au Sb, As
vapor, react with country rocks, and Foley and others,
mix with groundwater. The broad High sulfidation Cu, Ag, Au Sn, Sb, As, Te, Bi 2012; Hofstra
spectrum of deposit types results Lithocap alunite Al, K2SO4 Al, K2SO4, Ga and others, 2014;
from the large thermal and chemical Lithocap kaolinite Kaolin Ga London, 2016;
gradients in these systems. At deep Audétat and Li,
levels, NYF pegmatites emanate Fluorspar Fluorite Fluorite 2017
from plutons. Volcanogenic beryllium Be, U Be, U, Li
Volcanogenic uranium U U, Li, Be
Rhoylite tin Sn SnTable 1. Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative. —Continued
[±, present (absent); —, not applicable; ?, maybe; Ag, silver; Al, aluminum; As, arsenic; Au, gold; B, boron; Ba, barium; Be, beryllium; Bi, bismuth; Br, bromine; Ca, calcium; Cd, cadmium; Co, cobalt; CO2,
carbon dioxide; Cs, cesium; Cr, chromium; Cu, copper; F, fluorine; Fe, iron; Ga, gallium; Ge, germanium; Hf, hafnium; Hg, mercury; I, iodine; In, indium; IS, intermediate sulfidation; K, potassium; LCT,
lithium-cesium-tantalum; Li, lithium; Mg, magnesium; Mn, manganese; Mo, molybdenum; Na, sodium; Nb, niobium; Ni, nickel; NYF, niobium-yttrium-fluorine; P, phosphorus; Pb, lead; PGE, platinum group
elements; R, replacement; Rb, rubidium; Re, rhenium; REE, rare earth elements; S, skarn; Sb, antimony; Sc, scandium; SE, selenium; Sn, tin; Sr, strontium; Ta, tantalum; Te, tellurium; Th, thorium; Ti, titanium;
Tl, thallium; U, uranium; V, vanadium; W, tungsten; Y, yttrium; Zn, zinc; Zr, zirconium]
System name Synopsis Deposit types Principal commodities Critical minerals1 Reference(s)
IOA-IOCG IOA-IOCG systems form in both Albitite uranium U U Williams and others,
subduction- and rift-related mag- Iron oxide apatite Fe REE 2005; Cox and
matic provinces. IOA deposits Singer, 2007;
Iron oxide copper gold Cu, Au, U, Co, Se U, Co
form as hot brine discharged from Groves and others,
subvolcanic mafic to intermedi- Skarn iron Fe, P REE, Ge 2010; Slack, 2013;
ate composition intrusions reacts Polymetallic sulfide S-R-V Ni, Co, Mo, Cu, Zn, Pb, Ag, Au Co, Re, Ge, Ga, Barton, 2014;
with cool country rocks. Albitite In, Bi, Te, Sb, Slack and others,
uranium deposits form at deeper As 2016
levels where brines albitize country
Replacement manganese Mn Mn, Co
rocks. IOCG deposits form on the
roof or periphery of IOA mineraliza- Lacustrine iron Fe —
tion at lower temperatures, often
with involvement of external fluids.
Polymetallic skarn, replacement, and
vein deposits occur outboard from
IOCG deposits. Mn replacement and
lacustrine Fe deposits form near or
at the paleosurface.
Magmatic REE Magmatic REE systems typically occur Peralkaline syenite/ granite/rhyo- REE, Y, Zr, Hf, Nb, Ta, Be, U, REE, Zr, Hf, Nb, Verplanck and others,
in continental rifts or along trans- lite/ alaskite/pegmatites Th, Cu Ta, Be, U 2014, 2016;
lithospheric structures. REE and Carbonatite REE, P, Y, Nb, Ba, Sr, U, Th, REE, Nb, Sc, U, Dostal, 2016
other elements in mantle-derived Cu Sr, Ba, P, Cu,
ultrabasic, alkaline, and peralkaline Zr, magnetite,
(agpaitic) intrusions are enriched by vermiculite
Table Rationale and Explanation
fractionation and separation of im-
Phosphate REE, P —
miscible carbonatite melts ± saline
hydrothermal liquids.
15Table 1. Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative. —Continued
16
[±, present (absent); —, not applicable; ?, maybe; Ag, silver; Al, aluminum; As, arsenic; Au, gold; B, boron; Ba, barium; Be, beryllium; Bi, bismuth; Br, bromine; Ca, calcium; Cd, cadmium; Co, cobalt; CO2,
carbon dioxide; Cs, cesium; Cr, chromium; Cu, copper; F, fluorine; Fe, iron; Ga, gallium; Ge, germanium; Hf, hafnium; Hg, mercury; I, iodine; In, indium; IS, intermediate sulfidation; K, potassium; LCT,
Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative
lithium-cesium-tantalum; Li, lithium; Mg, magnesium; Mn, manganese; Mo, molybdenum; Na, sodium; Nb, niobium; Ni, nickel; NYF, niobium-yttrium-fluorine; P, phosphorus; Pb, lead; PGE, platinum group
elements; R, replacement; Rb, rubidium; Re, rhenium; REE, rare earth elements; S, skarn; Sb, antimony; Sc, scandium; SE, selenium; Sn, tin; Sr, strontium; Ta, tantalum; Te, tellurium; Th, thorium; Ti, titanium;
Tl, thallium; U, uranium; V, vanadium; W, tungsten; Y, yttrium; Zn, zinc; Zr, zirconium]
System name Synopsis Deposit types Principal commodities Critical minerals1 Reference(s)
Mafic magmatic Mafic magmatic systems generally Chromite Cr Cr Ash, 1996; Schulte
form in large igneous provinces re- Nickel-copper-PGE sulfide Ni, Cu, Co, PGE, Ag, Au, Se, Te Co, PGE, Te and others, 2012;
lated to mantle plumes or meteorite Ernst and Jowitt,
PGE (low sulfide) PGE PGE
impacts. Nickel-copper sulfide ores 2013; Woodruff
with PGEs result from settling and Iron-titanium oxide Fe, Ti, V, P Ti, V, REE and others, 2013;
accumulation of immiscible sulfide Zientek and
liquids in mafic layered intrusions others, 2017;
and ultramafic magma conduits. In Mondal and
layered intrusions, Fe-Ti oxides, Griffin, 2018
chromite, and PGE minerals crystal-
ize from evolving parental magmas
and are concentrated by physical
processes in cumulate layers. In
anorthosites, Fe-Ti oxides ± apatite
crystalize from residual magmas
entrained in plagioclase-melt diapirs.
In convergent settings, Alaskan-type
intrusions with Fe-Ti oxides and
PGE form from mantle melts.
1Elements in bold have been produced from some deposits, whereas those in italics are potential critical minerals.References Cited 17
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